The standard MRI apparatuses are those that use cylindrical magnets for generating a static magnetic field which makes the inside of the cylinder the imaging region, and also those that use a pair of magnets facing each other for generating a static magnetic field which makes the space between the magnets the imaging region. The magnets generally used for generating the static magnetic field are permanent magnets, normal-conducting magnets, or super-conducting magnets.
As for the MRI apparatus that uses the facing arrangement type of static magnetic field generating magnets, for example as illustrated in Patent Document 1, the known configuration places the gradient magnetic field coil on the imaging region side of the static magnetic field generating magnets, and also places the support member of the gradient magnetic field coil and the static magnetic field adjustment unit comprised of a plurality of magnetic pieces between the gradient magnetic field coil and the static magnetic field generating magnets. However, in this configuration the static magnetic field generating magnets pull the static magnetic field adjustment unit and causes distortion as a result, and it also causes distortion on the support member of the gradient magnetic field coil. This distortion creates an air gap between the gradient magnetic field coil and the support member, and the supporting effect of the member becomes imperfect because of it. The vibration is usually generated in the gradient magnetic field coil by Lorenzo force due to pulsed electric current, but the vibration tends to get bigger when the supporting effect of the support member is deficient. In Patent Document 1, to solve this problem a height adjustment means is placed between the gradient magnetic field coil and support member thereof to avoid having the air gap. Vibration of the gradient magnetic field is retrained by this means.                Patent Document 1: JP-A-2002-102206        
According to the configuration being disclosed in the above-mentioned Patent Document 1, the vibration of the gradient magnetic field transmits to the static magnetic field correcting unit because the support member of the gradient magnetic field coil and the static magnetic field correcting unit are contiguous to each other. This leads to the problem of vibration being transmitted to the static magnetic field. Also, because the magnetic field adjusting unit in Patent Document 1 is not provided with a vibration-damping function, there is a need to provide an additional damping member. In order to provide an additional vibration-damping member, the interval between the gradient magnetic field coil and the static magnetic field generating unit needs to be expanded to enable the setting of a damping member. As a result, it leads to the problem of narrowing the imaging region for placing an object to be examined.
There is a need for a MRI apparatus with reduced vibration in the gradient magnetic field coil which does not transmit the vibration to the static magnetic field correcting unit, and can further save space occupied by the static magnetic field correcting unit executing the vibration-damping.